Intelligent Power Today Magazine

IEEE Method Vs. the NFPA 70E Tables: Evaluating arc flash analysis methods

BY REZA TAJALI, Schneider Electric

Recent changes in workplace safety regulations have heightened the awareness of hazards associated with electrical arcs. The hazard level must be quantified and workers properly protected before entering proximity of exposed energized conductors. National Fire Protection Association’s (NFPA) standard 70E: “Standard for Electrical Safety in the Workplace” provides the guidelines for work involving electrical hazards and the selection of arc flash protective equipment.

In order to select the protective gear properly, one must have knowledge of the potential thermal energy of the electric...

Absence of voltage testing is a vital step in the process of verifying and establishing a de-energized state of any electrical system. As detailed in NFPA 70E clause 4.2.5., there is a specific and approved approach to establishing an electrical safe work condition with the following steps:

• determine all possible source of electrical supply
• interrupt the load current, open the disconnecting device for each possible source
• verify where possible that all blades of the disconnecting devices are open
• release or block any stored energy
• apply lockout device in accordance with documented and established work procedures
• using an adequately rated portable...